The use of colorants derived from plants or other pigmented natural resources goes back thousands of years in human history. Such pigments were widely used for dyes, and to some extent, for facial adornment. Since the preparation of any type of pigment-containing product was necessarily done on a short-term, small-scale basis in the ancient world, however, the inherent difficulties associated with the use of these materials, particularly with regard to stability, presented little concern.
What was acceptable in biblical times, however, is not acceptable today. Color cosmetics are now the basis for a huge industry, and preparation of these compositions is no longer relegated to the royal cosmetician or the local apothecary. The products sold today must meet high governmental regulatory standards, must have a reasonable compatibility with a wide variety of solvent systems and formulation variations, and particularly must be able to withstand the rigors of long-term storage and transportation. As most, if not all, natural pigments have a tendency to bleed, fade, or otherwise deteriorate in a very short period of time, the requirements of modern cosmetics cannot be met by their use. Therefore, the cosmetics industry has turned primarily to the use of inorganic pigments, such as metal oxides, or synthetic organic pigments, which can withstand assaults on stability, such as water, oxidation, light and temperature extremes. Even these pigments have their own share of stability problems; nonetheless, they are, overall, much more stable than the average natural pigment. Notwithstanding the superior stability and general flexibility of the oxides and synthetic pigments, however, consumers are now increasingly demanding a return to what are perceived as more "natural" products. To meet this demand, therefore, there is a continuing need to find ways to enhance the stability of naturally occurring pigments, to the extent that they can be used in cosmetics that can be stored for long periods, yet retain their color and not add significantly to the cost of the final product.
There have been many reports in the industry as to methods for stabilizing natural pigments. However, to date, none have found widespread commercial application in the cosmetics industry, perhaps because many are designed for use only with a specific kind of pigment, and the resulting pigment is useful only with one particular kind of solvent system. Therefore,